This invention relates to mechanisms for improved viewing of objects in low visibility atmospheres (e.g., in fog, smoke, dusty conditions, snow or rain, etc.).
When lights are used in attempts to penetrate low visibility atmospheres considerable glare is generated. Glare is partially responsible for the limited distance one is able to see in low visibility atmospheres. Increasing light intensity in an attempt to see further in low visibility atmospheres increases glare; as glare increases, diminishing returns are realized for further increases in light intensity. Eventually a point is reached where further increases in light intensity increase glare to such an extent that the distance one is able to see in the low visibility atmosphere is lessened.
Under my invention, improved viewing is accomplished by minimizing the effects of glare (thereby allowing use of higher intensity lights). Glare reduction is achieved by viewing only a short interval of distance ahead at a time (to the exclusion of all other intervals), and sequentially viewing succeeding intervals of distance one at a time. These distance intervals are designed to be shorter than the distance the unaided eye can see in the illuminated low visibility atmosphere.
My invention can be used with various types of lighting systems, e.g., automobile headlights; airplane landing lights; laser lights; portable lamps used or worn by miners, telephone repairmen or soldiers; or search lights on military, nautical or emergency vehicles.
The invention contemplates a light pulsing system for illumination. The pulsing light source can be a conventional light source and an electronic shutter cooperatively arranged to generate light pulses of predetermined duration and predetermined spacing. Alternately, the pulsing light source can be a pulsed laser or similar light element. In most cases, the time duration of each light pulse is materially less than the time spacing between successive pulses, e.g., a pulse duration of 0.1 microsecond and a pulse spacing of 1 microsecond. Return light from the viewed object (target) is controlled by a second shutter that is gated (opened and closed) at appropriate instants and for appropriate time durations relative to the pulse generation time, such that the human viewer sees only objects located predetermined distances away from the viewer. The second shutter ensures that the viewer will see objects illuminated by the light pulse after that pulse has travelled a predetermined distance (toward said objects and back to the viewer); objects closer to, or further away from, the viewer are excluded from the illuminated scene passed through the second shutter.
Objects of the invention are to provide an illumination-viewing system wherein:
1. Only objects within prespecified distance intervals are viewed at any one instant.
2. Undesired light reflections and glare from objects outside the prespecified distance intervals are eliminated from view.
3. Different prespecified distance intervals can be selected, varied, or sequenced, such that the human viewer can practically simultaneously preceive objects in different distance intervals.
4. Undesired glare generated outside the prespecified distance intervals can be excluded from view.
5. Contrast between objects within the prespecified distance interval and ambient low visibility atmosphere glare is enhanced.